4种通气模式对严重烟雾吸入伤犬早期血流动力学的影响

Effect of 4 mechanical ventilation modes on hemodynamics of dogs in early stage after severe smoke inhalation injury

目的 观察 4种通气模式对严重烟雾吸入伤犬早期血流动力学的影响。方法 3 5只犬分为PEEP组、PC组、CPAP组、IRV组和对照组。伤后 1h开始连续 2 4h机械通气。FiO2 =0 4,,PIP =16cmH2 O ,PEEP/CPAP =6cmH2 O ,除IRV组I∶E =2∶1外 ,其他通气组I∶E =1∶2。结果 各通气组治疗初期CVP、PAP、PCWP、PVR呈不同程度升高 ,2 4h呈回降趋势 ;各通气组分别于伤后 6h或12h降至最低点后呈回升趋势 ,但对照组CI呈进行性降低。结论 本实验所采用的通气模式及参数于烟雾吸入伤早期持续 2 4h通气治疗对血流动力学无明显不良影响 ,初期对血流动力学的影响与平均气道压水平关系较密切 ;机械通气在改善机体供氧的同时 ,可在一定程度上改善肺循环 ,增加心排血量 ;其中 ,CPAP组、PC组对血流动力学的影响小于PEEP组和IRV组。

Objective To observe the effect of 4 mechanical ventilation modes on hemodynamics in early stage after severe smoke inhalation injury in dogs. Methods A total of 35 dogs after smoke inhalation injury were equally divided into 5 groups according to different ventilation modes, that is, positive end expiratory pressure (PEEP), pressure control (PC), continuous positive airway pressure (CPAP), inverse ratio ventilation (IRV), and control. Continuous 24 hour mechanical ventilation was performed with same breathing machine 1 h after smoke inhalation injury at FiO 2 of 0.4, PIP of 16 cmH 2O, PEEP/CPAP of 6 cmH 2O, I∶E of 2∶1 in IRV group, and I∶E of 1∶2 in other ventilation groups. Results CVP, PAP, PCWP, and PVR increased to different degree in the early period after mechanical ventilation in 4 ventilation groups and showed descending trend 24 h after injury. CI decreased to the lowest point 6 h or 12 h after injury in 4 ventilation groups and then showed increasing trend, but progressive decreased in control group. Conclusion Modes and parameters at continuous 24-hour mechanical ventilation have no remarkable negative effects on hemodynamics in early stage after smoke inhalation injury. Hemodynamic depression in the early period of mechanical ventilation depends on the level of mean airway pressure. Following the improvement of oxygen delivery capacity, mechanical ventilation can improve pulmonary circulation and increase cardiac output to certain degree. The CPAP and PC groups have less effect on hemodynamics than those in PEEP and IRV groups.